Supported hydrogenation and hydrotreating catalysts

ABSTRACT

A catalyst composition having superior hydrotreating activity which catalyst is comprised of salts and/or complexes of Group VIII metals with Group VI metal heteropolyacids on an inorganic oxide support material, wherein the concentration of Group VIII metal ranges from about 2 to 20 wt. %, and the concentration of Group VI metal ranges from 5 to 50 wt. %, which percents are on support and which catalyst composition is substantially free of free water.

FIELD OF THE INVENTION

The present invention relates to catalysts for heteroatom removal,particularly sulfur, from petroleum and synthetic fuel feedstocks. Thecatalyst is comprised of salts and/or complexes of a Group VIII metalwith a Group VI metal heteropolyacid, on a refractory support. Thepresent invention also relates to a method for preparing such catalystswherein the Group VIII metal is impregnated onto the refractory supportby use of a Group VIII metal salt of an acid and the Group VI metal isimpregnated into the support by way of a Group VI heteropolyacid,wherein the acid comprising the salt of the Group VIII metal is lessacidic than the heteropolyacid.

BACKGROUND OF THE INVENTION

Hydrotreating of petroleum feedstocks and various boiling fractionsthereof has become increasingly important because of more stringentproduct quality requirements. For example, governmental regulationsconcerning allowed limits of sulfur in petroleum products, such asdiesel fuel, become more limiting each year. Furthermore, the petroleumindustry foresees the time when it will have to turn to relatively highboiling feeds derived from such materials as coal, tar sands, oil-shale,and heavy crudes. Feeds derived from such materials generally containsignificantly more deleterious components, such as sulfur, nitrogen,oxygen, halides, and metals. Consequently, such feeds require aconsiderable amount of upgrading in order to reduce the content of suchcomponents, thereby making them more suitable for further processing,such as fluid catalytic cracking, catalytic reforming, etc.

Hydrotreating of hydrocarbonaceous feeds is well known in the art andusually requires treating the feed with hydrogen in the presence of asupported catalyst at hydrotreating conditions. The catalyst istypically comprised of a Group VI metal with one or more Group VIIImetals as promoters on a refractory support. Hydrotreating catalystswhich are particularly suitable for hydrodesulfurization orhydrodenitrogenation generally contain molybdenum or tungsten on aluminapromoted with a metal such as cobalt, nickel, iron, or a combinationthereof. Cobalt promoted molybdenum on alumina catalysts are most widelyused for hydrodesulfurization, while nickel promoted molybdenum onalumina catalysts are the most widely used for hydrodenitrogenation.

Further, "Novel Hydrotreating Catalysts Prepared From HeteropolyanionComplexes Impregnated On Alumina", by A. M. Maitra and N. W. Cant,Applied Catalysis, 48 (1989) pp. 187-197, teaches hydrotreatingcatalysts prepared by impregnating alumina with solutions ofheteropolyanions having the general structure [H_(w) A_(x) B_(y) O_(z)]^(n-), where A may be Co or Ni, and B may be Mo or W. These catalystswere tested for hydrodesulfurization and hydrodenitrogenation activityand were found to be less active than a standard commercialhydrotreating catalyst.

While catalysts containing molybdenum with nickel, cobalt, or both, arein extensive commercial use today, they have limitations with respect toremoving heteroatoms from heavy feeds, such as heavy coker gas oils andcoal derived gas oils. As the feeds become heavier, the content ofcondensed aromatic hydrocarbons, with and without heteroatoms,increases. These condensed aromatics can absorb strongly on the catalystsites reducing both the rate and extent of heteroatom removal.Consequently, there exists a need in the art for improved hydrotreatingcatalysts having increased activity toward such heavy feeds,particularly when the heteroatom to be removed is sulfur or nitrogen.

BRIEF DESCRIPTION OF THE FIGURE

The sole figure hereof shows the degree of desulfurization of a feedupon treatment with TN-8, a high activity commercial Mo-Ni-Co on aluminacatalyst versus residence time.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a catalystcomposition comprised of salts and/or complexes of a Group VIII metalwith a Group VI metal heteropolyacid on an inorganic oxide supportmaterial, wherein the concentration of Group VIII metal ranges fromabout 2 to 20 wt. %, and the concentration of Group VI metal ranges from5 to 50 wt. %, which percents are on support and which catalystcomposition is substantially free of free water

Also in accordance with the present invention is a method for preparingthe catalyst compositions of the present invention by:

(a) impregnating an inorganic oxide support material with a Group VIIImetal salt of an acid and with a Group VI heteropolyacid, wherein theacidity of the acid of the salt of the Group VIII metal is less thanthat of the Group VI heteropolyacid; and

(b) drying the impregnated inorganic oxide support under conditions suchthat substantially all of the free water is driven off and salt and/orcomplex of the Group VIII metal salt and Group VI metal heteropolyacidresults and is not decomposed during this drying step.

In one preferred embodiment of the present invention, the salt of theGroup VIII metal is selected from acetates, formates, citrates, oxides,hydroxides, and carbonates.

In another preferred embodiment of the present invention, theheteropolyacid is a phosphomolybdic or phosphotungstic acid and thesupport is alumina.

In another preferred embodiment of the present invention, the catalystis comprised of about 10 to 40 wt. % Mo, and 4 to 12 wt. % Ni and/or Coon an alumina support.

DETAILED DESCRIPTION OF THE INVENTION

A variety of feedstocks can be hydrotreated with the catalysts of thepresent invention, including hydrocarbonaceous fractions and wholefeeds. Non-limiting examples of such feeds include organic solvents,light, middle and heavy petroleum distillates, as well as petroleumresidual feeds. Other feedstocks include coal derived liquids, shale,oil, and heavy oils derived from tar sands.

In the practice of the present invention, a heteroatom containing feed,especially a sulfur and/or nitrogen containing feed, is contacted withhydrogen at hydrotreating conditions in the presence of a catalyst ofthe present invention. The catalyst is comprised of salts and/orcomplexes of Group VIII metal(s), preferably Co and/or Ni, morepreferably Co; with at least one Group VI metal heteropolyacid,preferably Mo and W, more preferably Mo, on an inorganic oxide support,preferably alumina. The Group VIII metal is present in an amount rangingfrom about 2 to 20 wt. %, preferably from about 4 to 12 wt. %. PreferredGroup VIII metals include Co, Ni, and Fe, with Co being most preferred.The preferred Group VI metal is Mo which is present in an amount rangingfrom about 5 to 50 wt. %, preferably from about 10 to 40 wt. %, and morepreferably form about 20 to 30 wt. %. All metals weight percents are onsupport. By "on support" we mean that the percents are based on theweight of the support. For example, if the support were to weight 100 g,then 20 wt. % Group VIII metal would mean that 20 g. of Group VIII metalwas on the support.

It is critical to the present invention that the Group VIII metal beincorporated into the support material by use of a Group VIII metal saltof an acid which has an acidity less than that of the Group VIheteropolyacid. If the acidity of the acid comprising the salt of theGroup VIII metal is not less than the acidity of the heteropolyacid acatalyst complex will not form. Non-limiting examples of Group VIIImetal salts of conjugate acids which are suitable for use hereinincludes acetates, formates, citrates, oxides, hydroxides, carbonates,and the like. Preferred are water soluble salts, more preferred are thewater soluble acetates and formates, and most preferred are theacetates.

The Group VI metal is incorporated into the support by use of aheteropolyacid. Any suitable heteropolyacid may be used in the practiceof the present invention, with the water soluble acids being preferred.A detailed description of heteropolyacids can be found in Topics inCurrent Chemistry 76, "Heteropoly Compounds of Molybdenum and Tungsten,by G. A. Tsigdinas, Springer-Verlag Berlin Heidelbery, 1978, which isincorporated herein by reference. Preferred are water solubleheteropolyacids, such as phosphomolybdic acid, phosphotungstic acid,silicomolybdic acid, and silicotungstic acid. Heteropolyacids soluble inorganic solvents for catalyst impregnation may also be used.Non-limiting examples of such organic solvents include alcohols, such asthe C₁ -C₈ aliphatic alcohols, preferably methanol.

Any suitable inorganic oxide support material may be used for thecatalyst of the present invention. Preferred are alumina andsilica-alumina. More preferred is alumina. Other refractory inorganiccompounds may also be used, non-limiting examples of which includezirconia, titania, magnesia, and the like. The alumina can be any of thealuminas conventionally used for hydrotreating catalyst. Such aluminasare generally porous amorphous alumina having an average pore size fromabout 50 to 200 Å, preferably from about 70 to 150 Å, and a surface areafrom about 50 to about 450 m² /g, preferably from about 100 to 300 m²/g.

It is also within the scope of the present invention to incorporateadditional Group VI and Group VIII metals onto an existing conventionalhydrotreating catalyst in order to raise the metals content to levelswhich in the conventional catalysts yield little or no additionalactivity as a result of such increased metals loading. Conventionalhydrotreating catalysts typically contain about 0.5 to 5 wt. % GroupVIII metal and about 3 to 18 wt. % Group VI metal on an inorganic oxidesupport, which is typically alumina. By practice of the presentinvention, the Group VIII metal content can be increased to 20 wt. % andthe Group VI metal content can be increased to 50 wt. %, withaccompanying increases in activity. The procedure for incorporatingthese additional metals on conventional hydrotreating catalysts is thesame as incorporating the metals onto a fresh support. That is, theadditional Group VIII metal is incorporated into the conventionalhydrotreating catalyst by way of a salt of an acid and the additionalGroup VI metal by way of a heteropolyacid, wherein the acid comprisingthe Group VIII metal salt is less acidic than the heteropolyacid.

As stated above, alumina and alumina-silica supports are preferred. Itis preferred that the support material of the present invention besurface modified with silica. It is also preferred when the support isan alumina-silica material it not contain more than about 35 wt. %silica.

The silica surface modifying agent is added to the support prior toincorporation of the catalytic metals. Any suitable silicon containingcompound can be used as the source of silica. For example, preferredsilica sources include tetraethylorthosilicate in a suitable organicsolvent, such as a C₁ -C₈ alcohol, preferably isopropyl alcohol.However, such sources as silanes, colloidal silica, silicon chlorides,or other organic silicon salts may also be used. Following impregnationwith the silica source, the catalyst is dried at temperatures up toabout 200° C. and calcined at temperatures ranging from about 300°C.-750° C., preferably from about 350° C. to 550° C. Calcination iseffective in converting a silicon containing source to silica.

The amount of silica used to modify the surface of the support will beat least an effective amount. That is at least that amount which willenhance the activity of the catalyst for heteroatom removal, preferablyat least that amount which will enhance the activity by at least about5%, more preferably by at least about 10%. This amount of silica willgenerally be at least about 0.5 wt. %, preferably at least about 1 wt. %either as silica or a silica source. More preferably, silica additionsshould range from about 1 to 25 wt. %, most preferably from about 2 to12 wt. %.

The Group VI and Group VIII metals can be incorporated into the supportusing any suitable technique, preferably by an incipient wetnesstechnique, which is well known in the art. While it is preferred that asolution containing all of the metal salts be prepared and used toimpregnate the support material in one or more impregnations, it isunderstood that each metal can be individually impregnated into thesupport in any order. For example, a solution of Group VIII salt of anacid can be used to impregnate the Group VIII metal into the support.The so impregnated support can than be dried and impregnated with theGroup VI heteropolyacid. For economical purposes, it is preferred thatone solution be used to impregnate all of the desired metals into thesupport simultaneously. Any suitable impregnation conditions may be usedfor the preparation of the catalysts of the present invention.Generally, such conditions will include treating the support materialwith the impregnation solution for an effective period of time, and atan effective temperature. By effective period of time we mean for atleast that amount of time in which substantially all of the metal thatwill be impregnated into the support will be impregnated. Generally,this amount of time will range from about 1 minute to about 48 hours,preferably from about 10 minutes to about 30 hours. An effectivetemperature will generally be from about 15° C. to about 100° C.,preferably from about 20° C. to about 75° C.

After impregnation and drying, a salt and/or complex of the Group VImetal(s) with the Group VIII metal(s) compounds is deposited on thesupport. It is critical to the present invention that this complex bemaintained until sulfiding, especially during the drying step. Thus,drying conditions are maintained after impregnation which will notsubstantially decompose the salt and/or complex. Suitable dryingconditions include drying the impregnated support under vacuum, up tothe decomposition temperature of the salt and/or complex. The dryingstep drives off the free water so that the resulting catalystcomposition is substantially free of free water. That is, free of waterwhich is not chemically bound to the catalyst composition, such as byhydration. Because it is critical to maintain the salt and/or complex onthe surface of the support prior to sulfiding, the impregnated supportis not calcined prior to sulfiding.

Prior to use, the catalyst is sulfided under conventional sulfidingconditions. This sulfiding may be accomplished in situ, namely in thereactor. For example, the catalyst can be brought into contact with asulfur-containing distillate in the presence of about 50 to 1,500 V/H/Vof a hydrogen-containing gas under conditions including a temperature ofabout 75° C. to 450° C., a pressure (total pressure) of about 10 to 2500psig, and a liquid hourly space velocity of about 0.3 to 2.0 V/H/V.After this sulfiding treatment, the sulfur-containing distillate isswitched over to the feedstock to be treated, and the operation isrestarted under operation conditions suitable for hydrotreating of thefeedstock. In addition to the above process, use may be made of aprocess for effecting sulfiding comprising either bringing the catalystinto direct contact with hydrogen sulfide or other sulfur compounds, orby adding the sulfur compound to a suitable distillate and bringing theresulting distillate into contact with the catalyst. Suitable sulfurcompounds, or sulfiding agents, which may be in the sulfur containingdistillate include dimethyl disulfide, butyl mercaptan, dimethylmercaptan, carbon disulfide, and the like.

Heteroatom removal conditions, especially hydrodesulfurization andhydrodenitrogenation conditions, will vary considerably depending onsuch things as the nature of the feed being treated, the nature of thenitrogen or sulfur being removed, the nature of the complexes beingremoved, the nature of the complexes employed, and the extent ofconversion, if any, desired. In general, however, the following (TableA) are typical conditions for hydrodesulfurization/hydrodenitrogenationof a naphtha boiling within a range of about 25° C. to about 210° C., adiesel fuel boiling within a range from about 170° C. to 350° C., aheavy gas oil boiling within a range of from about 325° C. to about 475°C., a lube oil feed boiling within a range of from about 290° to 500°C., or residuum containing from about 10 percent to about 50 wt. % ofmaterial boiling above about 575° C. The catalysts of the presentinvention are not only superior for the hydrotreating ofheteroatom-containing feedstocks, but they may also be used for thesaturation of aromatic compounds.

                  TABLE A                                                         ______________________________________                                                                            Hydrogen                                          Temp.,   Pressure Space Velocity                                                                          Gas Rate                                  Feed    °C.                                                                             psig     V/V/Hr.   SCF/B                                     ______________________________________                                        Naphtha 100-370  50-800    0.5-10   100-2000                                  Diesel  200-400  100-1500 0.4-6     200-6000                                  Heavy   260-430  250-2500 0.3-4     500-6000                                  Lube Oil                                                                              200-450  100-3000 0.2-5       100-10,000                              Residuum                                                                              340-450  500-5000 0.1-2      1000-10,000                              ______________________________________                                    

The following examples are presented to illustrate the invention andshould not be considered limiting in any way.

EXAMPLE I--CATALYST PREPARATION Alumina

The alumina used for this example, as well as for the followingexamples, was a 14/35 mesh alumina having a surface area of 162 m² /g. apore volume of 0.682 cc./g., containing 7.12% water, a wet bulk densityof 0.631 g./cc., and a dry bulk density was 0.5861 g./cc.

Impregnation Solution

A 44.0 cc. solution was prepared from 8.58 g. Co(Ac)₂.4H₂ O (23.66% Co),17.59 g. of phosphomolybdic acid (48.7% Mo) and 31.32 g. demineralizedwater. The density of this solution was 1.3066 g./cc.

First Impregnation (17548-78)

A sample of the above alumina (31.61 g.) was impregnated with 28.09 g.of the impregnation solution. The stirred mixture was covered andallowed to stand 30 minutes after which it was uncovered and air-driedwith stirring to remove 2.66 g. of water by evaporation. Thedry-appearing solid was then dried in an oil pump vacuum oven at 160° C.for two hours to yield 38.94 g. of dry solid.

Second Impregnation (17548-79)

The product from the first impregnation was hydrated in open air to pickup 2.00 g. adsorbed moisture. This solid was then impregnated asdescribed above with 23.52 g. of the impregnating solution and air-driedwith stirring to remove 2.28 g. of water. The product was then dried inthe vacuum oven for two hours at 160° C. to yield 46.19 g. of drycatalyst containing 6.21 wt. % Co, and 26.19 wt. % Mo, both on dryalumina.

EXAMPLE II--CATALYST TEST PROCEDURE Reactor and Charge

40.0 cc. of 14/35 mesh catalyst was charged to a 29" long U-Tube reactorconstructed of 18 gauge 304 stainless steel. The reactor was immersed ina sand bath and attached to piping connected to a feed pump and ahydrogen source on the inlet and to a Mity Mite pressure controller, acondenser and a wet test meter on the exit side. Hydrogen flow rate wascontrolled with a flow meter.

Catalyst Sulfiding Conditions

The sulfiding feed used in this example comprised 7.4 wt. % of dimethyldisulfide and 92.6 wt. % of petroleum distillate. The petroleumdistillate contained 0.935 wt. % sulphur, 74 wppm nitrogen, 85.44 wt. %C and 13.32 wt. % H.

With the sand bath at 200° F., hydrogen flow was started at 0 minutesand pressure adjusted to 300 psig. Hydrogen gas flow was then adjustedto maintain an exit gas rate, as measured on the Wet Test meter, of 0.30l./min. At 2 minutes sulfiding feed was started at the rate of 20cc./min. At 5 minutes the feed rate was reduced to 1.0 cc./min. andheating of the sand bath started. At 65 minutes the sand bathtemperature was 450° F. This temperature was held while maintaining theliquid and H₂ flow until 725 minutes.

At this point the sand bath temperature was raised to 650° F. overapproximately 45 minutes (770 minutes) and the reaction maintained underthese conditions to 1055 minutes.

At this time the pressure in the reactor was raised to 500 psig, thereactor was blocked off under pressure with valves that are on both theinlet and exit lines, all flows stopped, and the reactor disconnected,removed from the sand bath and plunged into ice water.

At this point the catalyst was sulfided and ready for testing.

Testing of Catalyst

Feedstock used for testing activity of catalyst was 600+° F. bottomsfrom light catalytic cycle oil containing 2.148 wt. % sulfur, 1437 ppmN., 89.13% C and 8.07% H.

The reactor containing the catalyst which was sulfided as describedabove and stored under pressure was immersed in the sand bath at 650°F., the lines connected to the inlet and exit systems and the valvesopened. Feed was started at 1.5 cc./min. and H₂ at 0.45 l./min. asdetermined by the Wet Test meter on the exit line. Three liquid productswere taken at 1 hour 20 minute intervals followed by three products at40 minute intervals.

Product Workup

The liquid products were sprayed thoroughly with N₂ to remove all tracesof H₂ S and analyzed for sulfur using a Philips PW1400 x-rayfluorescence spectrometer.

Activity Evaluation

Catalyst activity was determined by comparison with the performance ofTN-8 sold by Akzo Catalysts. TN-8 is a NiCoMo on alumina hydrotreatingcatalyst having the following reported properties: apparent bulk density590 kg/m³ ; surface area 285 m² /g; pore volume 0.53 ml/g; with theshape being quadralobe. TN-8 is a state of the art hydrodesulfurizationcatalyst which for purposes of these examples is assigned an activity of100%.

The catalysts of these examples were rated vs. TN-8 on the basis of thereaction time required to reach a given degree of desulfurization inrelation to that time required by TN-8. To do this, a calibration curvewas prepared for TN-8 with the above-described feedstock and under theabovedescribed test conditions, but with feed rate (reaction time)varied widely (see attached FIG. 1). With this curve, a single test ofan experimental catalyst suffices to assess its activity. Thus, if anexperimental catalyst reaches a certain level of desulfurization inone-half the time required by TN-8, its activity would be 200%; or, ifan experimental catalyst requires 1.5 times as long to reach the degreeof desulfurization as does TN-8, the activity would be 1/1.5×100=67%.

EXAMPLE III--(Run 251, 17643-68)

The Catalyst of Example I was evaluated according to the procedure ofExample II and found to have 142% of the desulfurization activity ofTN-8 catalyst. The degree of nitrogen removal was 25%.

EXAMPLE IV--(17794-75)

An impregnation mixture weighing 55.19 g. was made from 9.42 g.Co(formate)₂.2H₂ O, 28.62 g. phosphomolybdic acid and 17.15 g.demineralized water. Alumina (63.11 g.), described in Example I exceptcontaining 7.44% adsorbed moisture and being in 1/16" extrudate form,was impregnated with the solution at room temperature (about 23° C.),allowed to stand overnight, then dried two hours in a 160° C. oil pumpvacuum oven. The dried catalyst weighed 89.77 g.

This catalyst was cracked and screened to 14/35 mesh and tested (Run366) according to the procedure of Example II. Desulfurization activitycorresponding to 88% of TN-8 activity was found. The degree of nitrogenremoval was 15%.

EXAMPLE V--(17794-47)

An impregnation mixture weighing 54.90 g. was made from 6.04 g oftechnical grade Co(OH)₂, 28.62 g. phosphomolybdic acid and 20.24 g.demineralized water. Alumina (63.19 g.), described in Example I exceptcontaining 7.57% adsorbed moisture and being in 1/16" extrudate form,was impregnated with the solution at room temperature, allowed to standovernight, then dried two hours in a 160° C. oil pump vacuum oven. Thedried catalyst weighed 87.07 g.

This catalyst was cracked and screened to 14/35 mesh and tested (Run368) according to the procedure of Example II. Desulfurization activitycorresponding to 91% of TN-8 activity was found. Nitrogen removal was16%.

EXAMPLE VI--(17794-75)

An impregnation mixture weighing 57.53 g. was made from 2.06 g. ofNi(Ac)₂.4H₂ O, 15.37 g. Co(Ac)₂.4H₂ O, 28.62 g. phosphomolybdic acid and11.48 g. demineralized water. Alumina (63.19 g.), described in Example Iexcept containing 7.57% adsorbed moisture and being in 1/16" extrudateform, was impregnated with the solution at room temperature, allowed tostand overnight, then dried two hours in a 160° C. oil pump vacuum oven.The dried catalyst weighed 91.63 g.

This catalyst was cracked and screened to 14/35 mesh and tested (Run370) according to the procedure of Example II. Desulfurization activitycorresponding to 133% of TN-8 activity was found.

EXAMPLE VII Alumina

The alumina used in this example was similar to that used in Example 1hereof except that it had a surface area of 223 m² /g and a pore volumeof 0.7406 cc./g. and contained 8.79 wt. % moisture. This alumina was inthe form of 1/20 in. quadralobe extrudate which was sized to 3 mmaverage length.

Silica Modified Support Preparation (17794-68)

A sample of 100 g. of the above alumina was impregnated with 10.894 g.of tetraethylorthosilicate diluted to 86 ml. with isopropyl alcohol andallowed to air dry overnight. The sample was then dried for 1 hr. in a160° C. oil pump vacuum oven, followed by calcination in a furnace at1000° F. for 1.5 hr. The recovered sample containing 3.44 wt. % SiO₂ (ondry Al₂ O₃) weighed 93.33 g. The surface area was 228 m² /g and the porevolume was 0.685 cc/g. Before impregnation, this support was hydrated to5.76 wt. % water content (on dry support plus water) by exposure to air.

Impregnation Solution

A solution was prepared by warming, for 15 minutes in a 57° C. waterbath, 15.37 g. Co(Ac)₂ 4H₂ O (23.66% Co), 28.62 wt. % phosphomolybdicacid (48.7% Mo) and 14.18 g. of dimeralized water.

Impregnation (17794-91)

The above described silica modified support (64.09 g.) was poured intosolution in a glass stoppered erlenmeyer and the mixture shakenvigorously for 2 minutes whereupon all the solution was absorbed by thesupport leaving dry-appearing particles. After 10 minutes the flask wasflushed with nitrogen and set aside at room temperature overnight (25hr.). The solid was then dried in a 160° C. oil pump vacuum oven for 2hours. The vacuum was broken with argon and the sample covered andallowed to cool to room temperature. The recovered catalyst weighed91.59 g.

The recovered catalyst was crushed and screened to 14/35 mesh (Tylerscreen size) for testing.

Determination of Activity of Catalyst (Run 367)

This catalyst was tested for activity according to the procedure ofExample II hereof and found to have an activity for desulfurization of153% of that of the comparative catalyst TN-8. The degree of nitrogenremoval was 27%.

What is claimed is:
 1. A method for preparing a catalyst composition suitable for removing heteroatoms from a heteroatom containing feedstock, which method comprises:(a) impregnating an inorganic oxide support material with a Group VIII metal salt of an acid and with a Group VI heteropolyacid, wherein the acidity of the acid of the salt of the Group VIII metal is less than that of the Group VI heteropolyacid composition selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, silicomolybdic acid, and silicotungstic acid; and wherein the Group VIII metal is selected from the group consisting of Fe, Ni, and Co; (b) drying the impregnated inorganic oxide support under conditions such that substantially all of the free water is driven off and salt and/or complex of the Group VIII metal salt and Group VI metal heteropolyacid results and is substantially not decomposed during the drying step; (c) sulfiding the product from step (b) in a petroleum distillate in the presence of an effective amount of sulfiding agent and at a temperature of about 75° C. to 450° C.
 2. The method of claim 1 wherein both the Group VIII and Group VI metals are impregnated from the same solution.
 3. The method of claim 1 wherein the Group VIII metal is selected from Co and Ni and a mixture thereof.
 4. The method of claim 3 wherein the acid comprising the salt of the Group VIII metal is selected from the group consisting of acetates, formates, citrates, oxides, hydroxides, and carbonates.
 5. The method of claim 1 wherein the inorganic oxide support is selected from alumina, silica, and alumina-silica.
 6. The method of claim 3 wherein the inorganic oxide support is selected from alumina, silica, and alumina-silica.
 7. The method of claim 1 wherein about 4 to 12 wt. % Group VIII metal and from about 10 to 40 wt. % Group VI metal are used.
 8. The method of claim 6 wherein about 4 to 12 wt. % Group VIII metal and from about 10 to 40 wt. % Group VI metal are used.
 9. The method of claim 1 wherein prior to impregnation the inorganic oxide support is modified with silica.
 10. The method of claim 8 wherein prior to impregnation the inorganic oxide support is modified with silica.
 11. The method of claim 9 wherein the silica source is tetraethylorthosilicate.
 12. The method of claim 10 wherein the silica source is tetraethylorthosilicate.
 13. The catalyst composition prepared by the process of claim 1, wherein the concentration of group VIII metal ranges from about 4 to 12% and the concentration of group VI metal ranges form about 10 to 40% based on the support.
 14. The catalyst composition of claim 13 wherein the surface of the support, prior to introduction of the metals, is modified with an effective amount of silica.
 15. The catalyst composition of claim 14 wherein the surface of the support is modified with tetraethylorthosilicate as the silica source.
 16. The catalyst composition of claim 15 wherein the Group VIII metal is selected from Co and Ni and a mixture thereof.
 17. The catalyst composition of claim 13 wherein the Group VIII metal is selected from Co and Ni and a mixture thereof.
 18. The catalyst composition of claim 13 wherein the inorganic oxide support is selected from alumina, silica, and alumina-silica.
 19. The catalyst composition of claim 17 wherein the inorganic oxide support is selected from alumina, silica, and alumina-silica. 